The Morris water navigation task, also known as the Morris water maze (should not be confused with water maze), is a behavioral procedure mostly used with rodents. It is widely used in behavioral neuroscience to study spatial learning and memory.[1] It enables learning, memory, and spatial working to be studied with great accuracy, and can also be used to assess damage to particular cortical regions of the brain.[1][2] It is used by neuroscientists to measure the effect of neurocognitive disorders on spatial learning and possible neural treatments, to test the effect of lesions to the brain in areas concerned with memory, and to study how age influences cognitive function and spatial learning.[1][3] The task is also used as a tool to study drug-abuse, neural systems, neurotransmitters, and brain development.[4][5]

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Schematic drawing of the Morris water navigation test for rats. Size and marker may vary.

A rat undergoing a Morris water navigation test

The basic procedure for the Morris water navigation task is that the rat is placed in a large circular pool and is required to find an invisible or visible platform that allows it to escape the water by using various cues.[3][6] Many factors can influence the rats' performance, including their sex, the environment in which they were raised, exposure to drugs, etc.[4] There are three basic tactics for the rats to escape the maze: a praxic strategy (remembering the movements needed to get to the platform), a taxic strategy (the rat uses visual cues to reach their destinations), or spatial strategy (using distal cues as points of reference to locate themselves).[7] There are a variety of paradigms for the water maze that can be used to examine different cognitive functions.[8] In particular, cognitive flexibility can be assessed using a water maze paradigm in which the hidden platform is continually re-located.[9]

The Morris water navigation task was conceived by Richard G. Morris (then at the University of St Andrews) in 1981 as an alternative to the radial maze.[10] The test was developed to study spatial learning and how it differed from other forms of associative learning.[11] Originally rats, now more commonly mice, were placed in an open pool and the latency to escape was measured for up to six trials a day for 2–14 days.[12] Several variables are used to evaluate an animal's performance. For example, a "probe trial" measures how long the test subject spends in the "target quadrant" (the quadrant with the hidden platform).[12] More elaborate trials alter the location of the hidden platform, or measure distance spent swimming in the pool before reaching the platform.[12] Over the years, many different versions of this test have been performed with a large amount of variables. For example, neuroscientists examine the effect of differences of sex, weight, strength, stress levels, age, and strain of species. The results vary dramatically, so researchers cannot draw conclusions unless these variables are kept constant.[1] Many different size pools have been used throughout the history of this task, but it has been shown that this does not have a significant impact on the results of the test.[13] In early versions of the task, researchers only timed latency to escape, however video tracking devices are now routinely used to measure the path to escape, time spent in each quadrant, and distance traveled in the pool.[14]

In Morris' first experiment, the apparatus was a large circular pool, 1.30 m across and 0.60 m high. The purpose of the original experiment was to show that spatial learning does not require the presence of local cues, meaning that rats can learn to locate an object without any auditory, visual, or olfactory cues.[15]

The earliest measure of learning is escape latency, which is the time it takes to find the platform. However, this measure is confounded by swimming speed, not necessarily a cognitive factor, and path length between point of origin and platform is a parameter more closely related to spatial learning.[16] Further parameters are the Gallagher measure,[17] the average distance to the platform, and the Whishaw corridor test,[18] which measures time and path in a strip directly leading from swim-start to platform. Other parameters are measured during probe trials: the escape platform is removed and the mice or rats are allowed to search for it for a fixed time (often 60 seconds). Variables measured are time and path length in quadrants, time near platform, and platform crossings.

Like other spatial tasks, such as the T-maze and radial arm maze, the Morris water navigation task is supposed to measure spatial memory, movement control, and cognitive mapping.[19][20] The T-maze and radial arm maze are much more structured in comparison.[21] The T-maze, for instance, only requires the rat or mouse to make a binary decision, choose left or right (or East or West). In the Morris water navigation task, on the other hand, the animal needs to decide continually where to go.[11] Another reason this task became popular is that rats (but not mice)[19] are natural swimmers, but dislike colder water (mice simply dislike water of any temperature), so in order to perform the task they do not need to be motivated by food deprivation or electrical shock.[11] The mobility of the platform allows for experiments on learning and relearning.[14] Also, the apparatus set-up and costs are relatively low.[14]

When the searching times for the platform in the target quadrant are reduced in the probe trial, this is seen as direct evidence that the spatial memory of the mouse must be impaired. However, many times the reason for a lengthier amount of time spent looking for the platform, or the lack of searching in the target quadrant, has nothing to do with an effect on the mouse's spatial memory, but is actually due to other factors. A large study of performance in mice concluded that almost half of all variance in performance scores was due to differences in thigmotaxis, the tendency of animals to stay close to the walls of the pool. About 20% of the variability was explained by differing tendencies of mice to float passively in the water until "rescued" by the experimenter. Differences in spatial memory were only the third factor, explaining just 13% of the variation between animals' performance.[16]

^Brandeis, R; Brandys, Y; Yehuda, S (September 1989). "The use of the Morris Water Maze in the study of memory and learning". The International Journal of Neuroscience. 48 (1–2): 29–69. doi:10.3109/00207458909002151. PMID2684886.

1.
Animal testing
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This approach can be contrasted with field studies in which animals are observed in their natural environments. Examples of applied research include testing, breeding, defense research and toxicology, in education, animal testing is sometimes a component of biology or psychology courses. The practice is regulated to varying degrees in different countries, worldwide it is estimated that the number of vertebrate animals—from zebrafish to non-human primates—ranges from the tens of millions to more than 100 million used annually. In the United States in 2014, official statistics indicate that 834,453 vertebrates were used in research, in the European Union, these species represent 93% of animals used in research. If the same was true in the United States, then the number of animals used in research is estimated to be between 12 and 25 million. One estimate of mice and rats used in the United States alone in 2001 was 80 million, in the European Union in 2011,11.5 million animals were used in research. Mice, rats, fish, amphibians and reptiles together account for over 85% of research animals, most animals are euthanized after being used in an experiment. Supporters of the use of animals in experiments, such as the British Royal Society, the terms animal testing, animal experimentation, animal research, in vivo testing, and vivisection have similar denotations but different connotations. Literally, vivisection means the cutting up of a living animal, the word has a negative connotation, implying torture, suffering, and death. The word vivisection is preferred by those opposed to this research, the earliest references to animal testing are found in the writings of the Greeks in the 2nd and 4th centuries BCE. Aristotle and Erasistratus were among the first to perform experiments on living animals, galen, a physician in 2nd-century Rome, dissected pigs and goats, and is known as the father of vivisection. Animals have repeatedly been used through the history of biomedical research, the founders, in 1831, of the Dublin Zoo were members of the medical profession, interested in studying the animals both while they were alive and when they were dead. In the 1880s, Louis Pasteur convincingly demonstrated the theory of medicine by inducing anthrax in sheep. In the 1880s, Robert Koch infected mice and guinea pigs with anthrax, in the 1890s, Ivan Pavlov famously used dogs to describe classical conditioning. In World War I, German agents infected sheep bound for Russia with anthrax, between 1917 and 1918, the Germans infected mules in Argentina bound for American forces, resulting in the death of 200 mules. Insulin was first isolated from dogs in 1922, and revolutionized the treatment of diabetes, on November 3,1957, a Soviet dog, Laika, became the first of many animals to orbit the earth. In the 1970s, antibiotic treatments and vaccines for leprosy were developed using armadillos and this genetic research progressed rapidly and, in 1996, Dolly the sheep was born, the first mammal to be cloned from an adult cell. Toxicology testing became important in the 20th century, in the 19th century, laws regulating drugs were more relaxed

2.
Alternatives to animal testing
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Alternatives to animal testing are the development and implementation of test methods that avoid the use of live animals. There is widespread agreement that a reduction in the number of animals used, two major alternatives to in vivo animal testing are in vitro cell culture techniques and in silico computer simulation. However, some claim they are not true alternatives because simulations use data from animal experiments and cell cultures often require animal derived products. Others say that they cannot replace animals completely as they are unlikely to provide enough information about the complex interactions of living systems. Other alternatives include the use of humans for skin irritancy tests, another alternative is so-called microdosing, in which the basic behaviour of drugs is assessed using human volunteers receiving doses well below those expected to produce whole-body effects. While microdosing produces important information about pharmacokinetics and pharmacodynamics it does not reveal information about toxicity or toxicology, furthermore, it was noted by the Fund for the Replacement of Animals in Medical Experiments that despite the use of microdosing, animal studies will still be required. Guiding principles for more use of animals in testing are the Three Rs first described by Russell. These principles are now followed in many testing establishments worldwide, Replacement refers to the preferred use of non-animal methods over animal methods whenever it is possible to achieve the same scientific aim. Reduction refers to methods that enable researchers to obtain levels of information from fewer animals. Refinement refers to methods that alleviate or minimize potential pain, suffering, or distress, cell culture can be an alternative to animal use in some cases. For example, cultured cells have developed to create monoclonal antibodies, prior to this, production required animals to undergo a procedure likely to cause pain. Skin irritation and skin corrosion refer to localized toxic effects resulting from an exposure of the skin to a substance. Human skin equivalent tests can be used to replace animal-based corrosive and irritative studies, epiDerm from Mattek and EpiSkin and SkinEthic RHE model are derived from human skin cells which have been cultured to produce a model of human skin. These methods are currently accepted replacements in Canada and the European Union, in August 2010, the Organisation for Economic Co-operation and Development published the Test Guideline 439 which describes the new procedure for in vitro hazard identification of irritant chemicals. Another synthetic replacement uses a membrane to simulate a skin barrier and is approved as a partial replacement by the US Department of Transportation. Several tissue culture methods which measure the rate of absorption by the skin have been approved by the OECD. Phototoxicity is a rash, swelling or inflammation, like a severe sunburn, the 3T3 Neutral Red Uptake Phototoxicity Test, approved by the OECD, detects the viability of 3T3 cells after exposure to a chemical in the presence or absence of light. Although originally derived from an embryo, the 3T3 cell line was developed in 1962

3.
History of animal testing
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Galen, a physician in 2nd-century Rome, dissected pigs and goats, and is known as the Father of Vivisection. In 1242, Ibn al-Nafis provided accurate descriptions of the circulation of blood in mammals, a complete description of this circulation was later provided in the 17th century by William Harvey. In his unfinished 1627 utopian novel, New Atlantis, scientist and philosopher Francis Bacon proposed a research center containing parks and enclosures of all sorts of beasts, for dissections and trials, that thereby we may take light what may be wrought upon the body of man. In the 1660s, the physicist Robert Boyle conducted many experiments with a pump to investigate the effects of rarefied air, in the 18th century, Antoine Lavoisier decided to use a guinea pig in a calorimeter because he wanted to prove that respiration was a form of combustion. He had an impression that combustion and respiration are chemically identical, Lavoisier demonstrated this with the help of Pierre-Simon Laplace. They both carefully measured the amount of carbon dioxide and heat given off by a pig as it breathed. Then they contrasted this to the amount of heat produced when they burned carbon to produce the amount of carbon dioxide as had been exhaled by the guinea pig. Their conclusion made Lavoisier confident that respiration is a form of combustion, also, the result showed that the heat mammals produce through respiration allowed their bodies to be above room temperature. Stephen Hales measured blood pressure in the horse, in the 1880s, Louis Pasteur convincingly demonstrated the germ theory of medicine by giving anthrax to sheep. In the 1890s, Ivan Pavlov famously used dogs to describe classical conditioning, in 1921 Otto Loewi provided the first substantial evidence that neuronal communication with target cells occurred via chemical synapses. He extracted two hearts from frogs and left them beating in an ionic bath and he stimulated the attached Vagus nerve of the first heart and observed its beating slowed. When the second heart was placed in the bath of the first. His work was performed in an isolated frog nerve-muscle preparation, adrian was awarded a Nobel Prize for his work. In 1996 Dolly the sheep was born, the first mammal to be cloned from an adult cell, the process by which Dolly the sheep was cloned utilized a process known as nuclear transfer applied by lead scientist Ian Wilmut. Although other scientists were not immediately able to replicate the experiment, Wilmut argued that the experiment was indeed repeatable, there has been growing concern about both the methodology and the care of laboratory animals used in testing. There is increasing emphasis on more humane and compassionate treatment of animals, methodological concerns include factors that make animal study results less reproducible than intended. For example, a 2014 study from McGill University in Montreal, in the 1880s and 1890s, Emil von Behring isolated the diphtheria toxin and demonstrated its effects in guinea pigs. He went on to demonstrate immunity against diphtheria in animals in 1898 by injecting a mix of toxin and antitoxin and this work constituted in part the rationale for awarding von Behring the 1901 Nobel Prize in Physiology or Medicine

4.
History of model organisms
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The history of model organisms began with the idea that certain organisms can be studied and used to gain knowledge of other organisms or as a control for other organisms of the same species. Model organisms offer standards that serve as the basis for comparison of other organisms. Model organisms are made standard by limiting genetic variance, creating, hopefully and these early works in finding standards to compare organisms against continued into the 20th century as the first model organisms were brought into laboratories. Beginning in the early 1900s Drosophila entered the research laboratories and opened up the doors for other organisms like Tobacco mosaic virus, E. coli, C57BL/6. These organisms have led to advances in the past century. These discoveries made in the 1860s lay dormant for nearly forty years until they were rediscovered in 1900, mendel’s work was then correlated with what was being called chromosomes within the nucleus of each cell. The fruit fly Drosophila melanogaster made the jump from nature to laboratory animal in 1901, at Harvard University, Charles W. Woodworth suggested to William E. Castle that Drosophila might be used for genetical work, Castle, along with his students, then first brought the fly into their labs for experimental use. By 1903 William J. Moenkhaus had brought Drosophila back to his lab at Indiana University Med School, sometime in the year 1906 Drosophila was adopted by the man who would become very well known for his work with the flies, Thomas Hunt Morgan. A man by the name of Jacques Loeb also tried experimentation in mutations of Drosophila independently of Morgan’s work during the 1st decade of the twentieth century. Thomas Hunt Morgan is considered to be one of the most influential men in experimental biology during the twentieth century. He was one of the first in the field to realize the potential of mapping the chromosomes of Drosophila melanogaster and he would later expand his findings to a comparative study of other species. With careful and painstaking observation he and other Drosophilists were able to control for mutations, through many years of work like this standards of these flies have become quite uniform and are still used in research today. These flies, along all the original model organisms, were not domesticated. The flies had to cross the threshold of nature to become creatures of a second, not just flies, but other organisms were also being brought into the laboratories during the early 1900s and tried out as experimental creatures. With the expansion of animals used as test subjects in laboratories came more knowledge of each model organism was best suited for testing. Limitations of these animals’ testing abilities were discovered so the introduction of even more model organisms began as science progressed. Drosophila exist today as one of the more advanced forms of insects on the due to their rapid evolution

5.
Pain in animals
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In humans, pain is a distressing feeling often caused by intense or damaging stimuli. Whether animals apart from humans also experience pain is contentious, the standard measure of pain in humans is how a person reports that pain. Only the person experiencing the pain can know the quality and intensity. However, for animals, it is harder, if even possible. Just as with doctors and medics who sometimes share no common language with their patients, although there are numerous definitions of pain, almost all involve two key components. This is the ability to detect noxious stimuli which evoke a response that rapidly moves the entire animal, or the affected part of its body. The concept of nociception does not imply any adverse, subjective feeling – it is a reflex action, an example in humans would be the rapid withdrawal of a finger that has touched something hot – the withdrawal occurs before any sensation of pain is actually experienced. The second component is the experience of pain itself, or suffering – the internal, emotional interpretation of the nociceptive experience, again in humans, this is when the withdrawn finger begins to hurt, moments after the withdrawal. Pain is therefore a private, emotional experience, Pain cannot be directly measured in other animals, including other humans, responses to putatively painful stimuli can be measured, but not the experience itself. To address this problem when assessing the capacity of species to experience pain. This is based on the principle that if an animal responds to a stimulus in a way to ourselves. Nociception usually involves the transmission of a signal along a chain of nerve fibers from the site of a stimulus at the periphery to the spinal cord. This process evokes a reflex arc response generated at the spinal cord and not involving the brain, nociception is found, in one form or another, across all major animal taxa. Nociception can be observed using imaging techniques, and a physiological and behavioral response to nociception can be detected. The nerve impulses of the response may be conducted to the brain thereby registering the location, intensity, quality. This subjective component of pain involves conscious awareness of both the sensation and the unpleasantness, the brain processes underlying conscious awareness of the unpleasantness, are not well understood. However, a characteristic of pain is that pain can result in hyperalgesia and allodynia, when this heightened sensitisation occurs, the adaptive value is less clear. First, the pain arising from the heightened sensitisation can be disproportionate to the tissue damage caused

6.
Testing cosmetics on animals
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Testing cosmetics on animals is a type of animal testing used to test the safety and hypoallergenic properties of products for use by humans. Because of the harm done to the subjects, this testing is opposed by animal rights activists. Cosmetic animal testing is banned in the European Union, India, Israel, methods of testing cosmetics on animals include many different tests that are categorized differently based on which areas the cosmetics will be used for. Draize test, This is a method of testing that may cause irritation or corrosion to the skin or eye on animals, dermal sensitization, airway sensitization, endocrine disruption, and LD50. Acute toxicity, This test is used to determine danger of exposure to a chemical by mouth, skin, Rats and mice are injected in lethal dose 50. This test can cause convulsions, loss of motor function. Skin corrosivity or irritation, This method of test assesses the potential of a substance causing irreversible damage to the skin and it is typically performed on rabbits and involves putting chemicals on a shaved patch of skin. This determines the level of damage to the skin that includes itching, inflammation, swelling, skin sensitisation, This is a method that determines if a chemical causes an allergic reaction. The chemical adjuvant is injected to boost the immune system, in the past it was performed on guinea pigs, and applied on a shaved patch of skin. Substances are assessed based on appearance of skin, dermal penetration, Rats are mostly used in this method that analyzes moment of a chemical, and the penetration of the chemical in the bloodstream. Dermal penetration is a method that creates a better understanding of skin absorption, Cosmetics manufacturers who do not test on animals may now use in vitro screens to test for endpoints which can determine potential risk to humans with a very high sensitivity and specificity. By using safe ingredients from a list of 5,000 which have already been tested in conjunction with modern methods of cosmetics testing, epiSkin™, EpiDerm™ and SkinEthic—each composed of artificial human skin is an option for alternative testing. It can imitate the reaction actual human skin will have to a product and it is a safe animal free way of testing for skin reactions, also known as Pyrogen tests, to product chemicals. The program sets global standard of operations and sales, internationally headquartered companies can obtain certification from Cruelty Free International. Companies headquartered in the US and Canada can obtain certification from The Coalition for Consumer Information on Cosmetics In 2013 over 500 companies were certified, however, some companys certifications were revoked after it was discovered they continued to test on animals in Asia. There is a used in animal testing laboratories titled the Three Rs, Reduction, refinement. The approach of reduction is built upon the ethics to have a number of animal subjects being tested on for current. Refinement suggests the planned distress and pain caused to an animal subject be as little as possible, refinement focuses on making a home for the animals before entering testing grounds in order to elongate the life of laboratory animals

Reflex arc of a dog when its paw is stuck with a pin. The spinal cord responds to signals from receptors in the paw, producing a reflex withdrawal of the paw. This localized response does not involve brain processes that might mediate a consciousness of pain, though these might also occur.